I think it’s D because there is no need to take them if you are not pregnant
Internal temperature, I believe.
Look at your R-R ratio, depending on the time segment attributed to each square you can then do the math and find time between waves, then find the number of R waves in minute
Contraception has many methods but each artificial method may not protect all kinds of STD's. Other methods may only protect the bacterial type but not those that viral type or vice versa. The best way to protect oneself from STD is to have a monogamous relationship with an infected partner with full awareness of the fertility cycle.